The quantitative determination of analytes in body fluids is of great importance in the diagnoses and maintenance of certain physiological abnormalities. For example, lactate, cholesterol and bilirubin should be monitored in certain individuals. In particular, it is important that diabetic individuals frequently check the glucose level in their body fluids to regulate the glucose intake in their diets. The results of such tests can be used to determine what, if any, insulin or other medication needs to be administered. In one type of blood-glucose testing system, test sensors are used to test a sample of blood.
A test sensor contains biosensing or reagent material that reacts with blood glucose. One type of test sensor is a multilayer test sensor that includes a base and a lid. The base has been attached to the lid in the multi-layer test sensor. One method of attaching the base to the lid is lamination. The act of laminating the base and the lid often has high, less desirable tolerances. In other words, the laminating of the base and the lid tends to have variances that are less than desirable (i.e., +/−0.015 in.). When the lamination of the base and the lid is not properly aligned, the base and the lid are said to be misregistered.
An example of a misregistered base and lid is shown in prior art FIGS. 1a-c. FIG. 1a depicts a sensor-ribbon strip 10 that includes a base-ribbon strip 20 and a lid-ribbon strip 30. The base-ribbon strip 20 includes a plurality of laser cuts 22a-c that defines a plurality of conductive leads or traces 26a-d thereon. The conductive leads or traces are the lead portions of the electrodes. To better show the laser cuts 22a-c formed on the base-ribbon strip 20, the laser cuts 22a-c have been shown extending upwardly above respective apertures 28 formed in the lid-ribbon strip 30 even though they would be partially hidden by the lid-ribbon strip 30. Additionally, FIGS. 1a-c highlight only the areas that will form a portion of the conductive leads or traces, while the actual cuts to form the electrodes or other features of the test sensor are not depicted.
The lid-ribbon strip 30 of FIG. 1a forms a plurality of registration apertures 32a,b. The lid-ribbon strip 30 is laminated to the base-ribbon strip 20. As shown in FIG. 1a, the lamination of the lid-ribbon strip 30 and the base-ribbon strip 20 is not properly aligned (i.e., misregistered). The misregistration of the lid-ribbon strip 30 and the base-ribbon strip 20 of FIG. 1a results in conductive leads 26a-d being of unequal widths. Thus, the plurality of test sensors formed from the sensor-ribbon strip 10 would have conductive leads 26a-d of unequal widths.
When the base and the lid are misregistered, conductive problems between the conductive leads of the test sensor and the meter or instrument may result. For example, misregistration may result in a short between the conductive leads of the test sensors and contacts of the instrument. If a short occurs, the instrument produces an erroneous reading of an analyte concentration or does not produce any reading of the analyte concentration. Misregistration may also result in an erroneous reading of an analyte concentration because the areas of the conductive leads are incorrect.
Therefore, it would be desirable to use a method that eliminates the lamination tolerances of the base and the lid.